2016 International Conference on Applied Mechanics, Mechanical and Materials Engineering (AMMME 2016) ISBN: 978-1-60595-409-7 Application of Airborne Electro-Optical Platform with Shock Absorbers Hui YAN, Dong-sheng YANG, Tao YUAN, Xiang BI, and Hong-yuan JIANG* School of Mechatronic Engineering, Harbin Institute of Technology, Harbin, Heilongjiang, China *Corresponding author Keywords: Metal rubber, Damper, Photoelectric platform, Vibration isolation performance. Abstract. With the rapid development of information technology, the importance of access to information in today's increasingly demanding. And as today's new metal rubber vibration isolation material in the complex conditions of the various characteristics of the advantages make it airborne optoelectronic platform more widely. This article will focus on airborne optical platform shock absorber design, and by the designed shock absorber static and dynamic analysis of its experimental parameters influencing factors and variation of vibration isolation performance of the developed damper. For future airborne optical platform provides experimental basis with the development of shock absorber. Introduction With the rapid development of the aerospace industry, the application of vibration damping material will face new challenges, especially traditional vibration damping properties of structural materials and in some special cases also facing a severe test. During the period spacecraft service, more impact from vibration and shock, and in the cause of failure, and mostly due to engine and aerodynamic noise, it may cause serious broadband random vibration and noise environment, but also caused the accuracy of the formant structure and the fatigue failure of the electronic control electronic control equipment and instrumentation systems and many other institutions and even mechanical failure caused by power instability. Metal Rubber Technology Development Review Dry Friction Damping Isolation Brief Dry friction damping method more accurate discussion should be able to correctly describe the mathematical model proposed by dry rubbing method, the overall slide and the slide can be used as part of a dry friction sliding contact surfaces of a mathematical model in the different states. When the same tangential direction in the body contact region having a degree of elastic strain through a point external action throughout different points, and the relative sliding is possible, therefore, the contact area between the state of the object deformation representation. Overall slide, the main goal is to simplify the case of some special conditions proposed by frictional contact vibration mode, but it applies to smaller contact surface between the surface of the object or small load. However, in practice, the contact surface of the object in general will not have the same elastic deformation. When the external force increases, when the critical value in a certain area, the tangential strain point of contact between the object does not exceed the shear strain strain is still able to maintain a state of elastic deformation; a further increase in value when an external force in corresponding change much each point will make the entire contact area than the imum tangential strain itself is a large slippage of the entire contact area. Normal contact surface pressure is a necessary condition for large slippage. In general, dry frictional contact with the elastomer is a situation characteristic of the model based on the analysis of the sliding portion.
Preparation Process Description As an elastic porous metal rubber-like material, although metal is called rubber, but it is not made of metal and rubber composite made of simple, but by selecting the appropriate quality wire, through a special process for their preparation into a spiral shaped, stretched so that its pitch is equal to diameter of the screw, and then after the laying of cold stamping knit to shape, if necessary also need to be appropriate heat treatment to improve its mechanical properties. It has a large damping to absorb impact energy, strong resistance, high temperature capability is not easy to aging and other characteristics, so it has been widespread concern and attention in the aerospace and defense fields. Damper Structure and Performance Parameters Shock Absorber Design In structural design using traditional vibration mode, as shown in FIG airborne optical platform by a threaded connection to a central sleeve 1, the center set by the upper and lower sets of rubber-metal (3 and 4) of the inner wire slip form of dry friction damping effect to achieve, and then achieve the vibration is transmitted to the base 2 of the photoelectric platform vibration during weakening effect. In this design, the cover 6 is threaded sleeve and connect the center and connected by a threaded cover and center cover screwing length of the initial pre-control the amount of deformation of metal rubber parts, in order to achieve different conditions Work requirements. The design process, set in the center of the junction 1 and the base 2 can also leave some radial offset, in order to prevent displacement due to vibration during operation of the radial direction of the burst has caused the destruction of the shock absorber. Figure 1. Schematic diagram damper. Figure 2. Damper physical map.
Static Performance Parameters Figure 3 for the static deformation of the hysteresis loop linear damping system, an area which is surrounded by the hysteresis expressed shock absorber in one cycle by the dry friction damping dissipated energy, surrounded by the x-axis and the center line the area of the triangle represents a potential imum deformation cycle, and therefore the damping coefficient of energy consumption by the following formula: W 2π T ψ = W p 0 where, T 0 is the deformation at zero reaction force, P is the imum reaction force. (1) P T 0 W p p O T 0 x X ΔW Figure 3. Load - Deformation static deformation hysteresis loop. Approximate calculation formula of metal rubber damper stiffness for the average: k s where, p = x K s is the average stiffness isolator, Dynamic Characteristics X is the imum deformation. In the dynamic damper test performance analysis, the dynamic damper transfer rate is used to evaluate the performance of a damper important indicator. For harmonic vibration damping system sweep experiments, often the size of the vibration transmissibility to do the evaluation criteria for the transfer characteristics analysis. Acceleration transmissibility by harmonic vibration sweep test obtained output, the ratio of input acceleration was illustrated, namely the acceleration transfer rate [1,2] : (2) a η = a out in where, is the system output aceleration, is the system input accelerateon. (3) Experimental Research Static Analysis of Test Results Figure 4 and 5 respectively, by the use of Guilin Reiter testing machine Co. produced TCD-C computer numerical control machine spring testing initial denaturation at opposite different
relative density of metal rubber stiffness curve damper static test carried out and obtained by the static energy dissipation coefficient curve. Figure 4. Effect of different relative density of the isolation system stiffness ( Q = 0.1). Stiffness can be seen from the curve, the trend of metal rubber damper stiffness is nonlinear. Metal rubber damper in the amount of deformation amplitude settings less stiffness with increasing deformation amplitude decreases; when the magnitude of the deformation is gradually increased over a test range from time to time, metal rubber damper stiffness gradually increases Great, that was a hard force and deformation characteristics. Figure 5. Effect of different relative density on energy consumption coefficient ( Q = 0.1). Can be seen from the curve, changes in the relationship between energy consumption and deformation amplitude coefficient between the metal rubber damper is also non-linear process, and they can see the magnitude of the amount of deformation increases, drastically reduced its energy consumption coefficient small, because the size of the magnitude of the deformation may affect the relative density of the metal material is rubber, by the conclusion of the Figure 3-1 shows the stiffness is increased due to the relative density increases, the ability to consume the vibration energy will member because increased stiffness and reduced, so too will follow the energy dissipation coefficient decreases. Therefore, in the design of metal rubber damper, in order to ensure its isolation effect to control the deformation of the magnitude of the shock absorber. Metal rubber damper under the same conditions as the pre-deformation, the energy dissipation coefficient curve as the relative density increases downward movement, namely, the energy dissipation factor as the relative density increases. Dynamic Analysis of Test Results Figure 6 is the use by the Beijing Aerospace Aerospace Science and Technology Co., Ltd. Hill produced dynamic tester initial relative initial denaturation ( ) dynamic test different relative density = 0.1 of metal rubber damper conducted obtained acceleration transmissibility curve.
_ Figure 6. Effect of different relative density of the transfer rate ( Q = 0.1 ). As shown in the input acceleration of 1.5g under the conditions of vibration transmissibility curve obtained. As can be seen, the transfer curve of metal rubber parts will be the right move, because the static test will get its peak curve relative density increases with the increase, changing the relative density of the metal pieces of rubber will affect the inner contact wire the purpose of changing the number of points, so when increasing its relative density, stiffness will change due to the internal purpose of contact points increases. At the same time, and because the internal relative slippage of the wire will be affected by the relative density of the size and density of the metal due to the relative increase in damping properties of rubber parts relative slippage of the metal will be reduced due to reduced rubber parts. Thus, since the phase metal rubber parts for the density increase its transmitssibility curve peak and the resonance frequency is increased. Therefore, in the dry friction damping characteristics and properties of the natural frequency of the metal rubber parts of the analysis must consider the relative density of. Conclusions In this paper, Air Force Armament Department airborne optical platform applications with metal rubber damper for pre-research project as the background, to promote the use of metal rubber damper, to meet the real needs for the goal. Metal rubber shock absorber development, static and dynamic test and study mode characteristic parameters were tested to study for the development and application of metal rubber damper provides a theoretical and practical experimental basis, in order to meet the requirements of certain transfer rate metal rubber shock absorbers provide a realistic reference. References [1] Zhou Yun, Xu Tong, Yu Gongye, Li Xiping. Progress Energy dissipation technology research and application[j]. Earthquake Engineering, 1997: 28-33(in Chinese). [2] Zhuang Biaozhong, Xing Hong, Gao Zhan. The definition and application of nonlinear vibration isolator transmissibility[j]. Mechanical strength. 1991, 13(1):14-17(in Chinese).